Acylated 3, 6-pyridazinediones



A'CYLATED 3,6-PYRIDAZINEDIONES David Stefanye, Frederick, Md., WilliamL. Howard, Lake Jackson, Tex., James W. Brown and Robert L. Weintraub,Frederick, Md., assignors to the United States of America as representedby the Secretary of the Army N Drawing. Application July 17, 1957 SerialNo. 672,523

4 Claims. (Cl. 260250) (Granted under Title 35, US. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment to us of any royalty thereon.

This invention relates to the lower straight chain alkyl esters of 1,2dihydro-pyridazine 3,6-dione.

The preferred method of producing these esters is the acylation of a 1,2dihydro-pyridazine-3,6-dione, or an alkali salt thereof with a loweralkyl chloro-formate in a dilute aqueous sodium hydroxide solution. Thereactions may be represented as follows:

R is a lower straight chain alkyl group.

EXAMPLE I Maleic hydrazide (0.1 mol) is dissolved in a solution of 0.1mol of potassium hydroxide in water (75 ml.) with slight heating to aidsolution. A lower alkyl chloroformate is added after cooling to roomtemperature, and the resulting mixture is shaken for two hours. Thereaction mixture is then filtered and washed with 200 ml. of ligroine,and the filtered solid material recrystallized from a suitable solventto yield the ester.

United States Patent For example, if ethyl chloroformate is used toacylate I 1,2-dihydro-3,6-pyridazine dione, the ester, ethyl2,3-dihydro-3-oxo-6-pyridazinyl carbonate is formed, which readilycrystallizes from benzene without solvent of recrystallization; or ifbenzoyl chloride is used, the ester 2,3-dihydro-3-oxo-6-pyridazinylbenzoate is formed which readily crystallizes from alcohol withoutsolvent of recrystal- I lization. H

Higher homologs, such as prepared from the interaction of amylchloroformate and maleic hydrazide, are liquids at room temperature andmay be purified by distillation under reduced pressure.

These compounds have been found to have excellent properties asherbicides in inhibiting the growth of various types of broadleaved andcereal species. In establishing the herbicidal properties-of thesecompounds, tests were made by spray presentation on the plants and by'root elongation tests on sprouts. The spray presentation test, which isdesigned for primary screening of chemicals, was carried out as follows:

Four broadleaved and two cereal speciesBlack Valentine Beans, LincolnSoybeans, Heavenly Blue Morningglory, Scarlet Globe Radish, ClintonOats, and Collusa Rice-are grown from seed in a 2-1 soil-sand mixture inmetal window boxes (3 species per box) in a greenhouse. About one weekafter planting and about four days after emergence these species aresprayed with test compounds at rates of 0.1 and 1.0 lbs/acre. A pair ofwindow boxes containing the six species are sprayed with each rate ofeach compound.

The compounds are prepared in acetone solutions containing 1% Tween 20,or other suitable Wetting agent, or where they are not soluble inacetone, water plus 1% Tween 20 is tried as a solvent. When a compoundis not sufficiently soluble to test in either of these solutions and isnot a liquid itself, it is applied as a dust by weighing the desiredamounts into gelatin capsules which are then fired from a muzzle adaptorof a C0 pistol into a chamber containing the test plants. The adaptorshatters the capsule on firing. Immediately prior to this dryapplication the plants are sprayed with water containing.

-2. x percent inhibition where C=fresh weight of untreated plants 2weeks after treatment.

T =fresh Weight of treated plants 2 weeks after treatment.

Root elongation tests which are also designed for primary screening ofcompounds were carried out in the following manner:

The method of growing seeds of the above species consists of preparing3-inch wide strips of Whatman #1 filter paper, either 9 or 18 incheslong (depending on seed size), upon which an equal length of /2-inchwide pressure-sensitive tape is placed along one edge. A /2-iI1Ch stripof filter paper about 2 inches shorter than the pressure tape and having4-inch diameter holes on /z-inch or l-inch centers is mounted on top ofthe pressure tape. Fifteen individual seeds of a species are thenspotted on the exposed portions of the tape, the filter paper rolledwith the seeds inside, and the roll held closed by the extra length ofpressure tape. These rolls are then upended in 4-inch high paperdrinking cups which contain 70 ml. of solution to be tested. The papercups are then placed in metal trays 22 x 19 x 6 inches having perforatedfalse bottoms and containing a /z-inch layer of Water. The trays arecovered with glass and serve as humidity chambers. The trays are kept ata temperature of 8285 F. for 72 or 96 hours (depending upon theparticular species), after which period the seed rolls are opened andthe root lengths measured to the nearest centimeter. 0f the fifteenseeds planted, measurements are taken of the ten seeds producing thelongest roots. The average root length of the group of ten seeds is 3used for computing the percent inhibition of root elongation on anuntreated control basis:

(ll-6J2 X 100==percent inhibition Further evidence of the effectivenessof these esters is shown in the following tests where the numericalrating has the following efiectz' 1-No effect Where root elongation isobviously affected for some 2Slight effect reason other than thepresence of a test compound (e.g., 3 -M d rate fiect profuse fungalcontamination or control root lengths less 4-S ff t than an average of 5cm.), the test is rerun; When only a few seeds of a roll arecontaminated, the root lengths that the terms appearing at the head ofthe table have the of the remaining longest roots are obtained. If lessthan following significance: 7 seeds are suitable for measurement thetest is rerun. F ti E t T iti ml d m d f ti orma ve e ee 1 WS ng, W ngan 0 er 6 011118. On. It 1s estimated that at least 90% of the rollshave 10 Chlorosis: Spotting due to removal of pigmentaflm roots ofacceptable lengths. Contagt itujirsl': lgurnlng or other injury atpoints where spray con ac e p an The test soiuilons are prepare.d from aP' Stunting: Dimlnutive or dwarf formations. (parts per million) stocksolution of a compound in Necr0si ;1)eadening or tissue,

Forma- Contact Plant tlve Chlorosis Injury Stunting Necrosis CompoundEffect Black Valentine Beam... 3 1 1 2 1 1 1 l 4 1Buty-2,3-d1hydro-3-oxo- 2 1 1 1 1 pyridazinyl-ecarbonate. 1 1 1 1 1 a 11 2 1 1 1 1 4 1 Propyl-2.3-dlhydro-3oxo' 2 1 1 l 1pyridazinyl-fi-carbonate. 1 p 1 1 1 1 Black Valentine Bean. 3 1 1 2 1Soy Bean 1 1 1 4 1 ,Ethyl-2,3-dihydro-3-oxo- Morning Glory. 2 1 1 1 1pyridazinyl-ficarbonate. Radish 1 1 1 1 1 100% acetone, so that thefinal concentrations for test- These tests show the efiectiveness oflower straight chain ing are 0.1, l, and 10 p.p.m. aqueous solutionscontaining alkyl carbonate esters as herbicides. They are, more- 0.5acetone. A standard solution of 2,4-D is tested over, more efiectivethan the branched chain alkyl carboroutinely on each species each timeat the 1 p.p.m. level. nate esters or the benzoate or sulfonate estersof 1,2 Each test also contain' 5 an untreated control consisting ofdihydro pyridazine 3,6 dione. 0.5% acetone in tap water. Thisapplication is a continuation-in-part of application The results ofthese tests on several of the disclosed Serial No. 482,32 nowabandonedcompounds are shown in the following table: 40 We claim:

Results tests Pf lower W g chain Y esters f 1,2 1. A lower straightchain alkyl carbonate mono ester dlhydm pyrldazme'36 dmne of 1,2dihydro-pyridazine-3,6-dione.

Emma} Fromm} Ethy1 2,3 2. Ethyl carbonate monoester of 1,2dihydro-pyrida- Spray PresentationdihydroJi-oxodihydro3oxodihydro-H-oxoi s 6.di

Test On Plants-9 pyridnzinyl-G- pyridazinyl-G- pyrldazinyl-G- carbonatecarbmme carbmate 3. Propyl carbonate mono ester of 1,2-dihydro-pyrida-Application (lbs./

1 1 4. Butyl carbonate mono ester of 1,2 dihydro-pyridafl g g;zine-3,6-dione. -20 70 -2o 10 :3 i1 g 21; References Cited 1n the fileof this patent UNITED STATES PATENTS 1 Black Valentine Beans. Valuesgiven are in percent inhibition of growth. Negative values indicateaccentuation of growth.

2,614,917 Zukel et a1. Oct. 21, 1952

1. A LOWER DTRAIGHT CHAIN ALKYL CARBONATE MONO ESTER OF 1,2DIHYDRO-PYRIDAZINE-3,6-DINO.